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This master thesis deals with a special variant of the Vehicle Routing Problem (VRP), where there are many customers per road segment. This kind of VRP arises in many real-life situations, e.g. mail delivery and garbage collection. VRP solvers are part of most Decision Support Systems (DSS) used by companies in this business sector. In an operational(More)
We present a problem dealing with transportation of live animals to slaughterhouses. The problem is taken from the Norwegian meat industry, and may be viewed as a vehicle routing problem extended with constraints to ensure a smooth production flow at the abattoir. In addition, several constraints to ensure animal welfare have to be met. These include(More)
We provide a computable definition for the intuitive concept of the point of diminishing returns in a heuristic search. We also demonstrate that with proper scaling, the time point for a small instance can provide some guidance concerning the time point on larger instances. Computational results are presented for a range of problems and search methods.
We describe a special variant of the Vehicle Routing Problem (VRP), where there are many customers per road segment. A metaheuristic tabu search algorithm for the VRP is given, and aggregation of customers is used to better the performance, with respect to both time and solution quality. The methods are tested on test instances from the literature as well(More)
Oil tanker traffic constitutes a vital part of the maritime operations in the High North and is associated with considerable risk to the environment. As a consequence, the Norwegian Coastal Administration (NCA) administers a number of vessel traffic services (VTS) centers along the Norwegian coast, one of which is located in the town of Vardø, in the(More)
We describe an opportunity to speed up multi-stage scenario generation and reduction using a combination of two well known methods: the moment matching method (Høyland and Wallace 2001) and the method for scenario reduction to approximately minimize a metric (Heitsch and Römish 2009). Our suggestions is to combine them rather than using them in serial by(More)
Application of fish sludge as fertiliser to agricultural land can contribute to closing nutrient cycles in fish farming. The effect of different treatment technologies on the nitrogen fertilisation effects of fish sludge was studied by a bioassay with barley (Hordeum vulgare), an incubation and a field experiment. Dried fish sludge resulted in relative(More)